A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) to include an airworthiness directive (AD) that is applicable to certain McDonnell Douglas Model DC-9-14, DC-9-15, and DC-9-15F airplanes; and Model DC-9-20, DC-9-30, DC-9-40, and DC-9-50 series airplanes; was published in the Federal Register on January 29, 2004 (69 FR 4259). That action proposed to require, among other actions, performing repetitive inspections for cracking of the counterbore of the two lower mounting holes and the lower forward edge of the outboard idler hinge fitting of the left and right wing flap at station Xw=333.148, and replacing the flap idler hinge fitting with a new or serviceable part. \n\nComments \n\n\tInterested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received. \n\nSupport for Proposed Rule \n\n\tOne commenter supports the proposed rule. \n\nRequest ToRevise Cost Estimates \n\n\tThe other commenter, an operator, requests that we revise the cost estimates listed in the proposed rule. The commenter states that the inspection, based on similar inspections it is currently conducting for another AD, will take four work hours per airplane (two work hours per fitting, two fittings per airplane) instead of the two work hours estimated in the proposed rule. The commenter points out that Boeing Service Bulletin DC9-57-225 (referenced as the appropriate source of service information in the proposed rule) specifies 2.7 work hours per fitting, 5.4 work hours per airplane. The commenter further states that the proposed rule does not include the cost of replacement parts required at each inspection interval, at the cost of $1,122.20 per airplane (for Group 1 airplanes within its fleet). Therefore, the commenter declares that the proposed inspection will actually cost $1,365 per airplane, per inspection cycle for Group 1 airplanes, and $667 per airplane, per inspection cycle for Group 2 airplanes--not $130 per airplane, per inspection cycle, as proposed. \n\n\tThe commenter also states that the replacement will take nine work hours per fitting, instead of the two work hours estimated in the proposed rule. The commenter points out that Boeing Service Bulletin DC9-57-225 specifies 7.6 work hours per fitting for the replacement. Therefore, the commenter declares the proposed replacement will cost $6,005 per airplane for Group 1 airplanes, and $10,397 per airplane for Group 2 airplanes--instead of between $2,024 and $4,569 per airplane, as proposed. \n\n\tWe agree with part of the commenter's request. We have reviewed data provided by the airplane manufacturer and agree that replacement of some additional parts may be necessary during the required inspection and replacement. We do not agree, however, with the cost provided by the commenter for those parts. We have revised the cost information below to include the costs of those additional parts, based on the information provided to us by the airplane manufacturer. \n\n\tWe do not agree to revise the work hour estimate for the inspection or replacement. The commenter supplied no data to support its estimate of nine work hours for the replacement. The referenced service bulletin specifies two work hours per fitting for the replacement, which corresponds with the cost information below. We acknowledge that the referenced service bulletin specifies 2.7 work hours per fitting for the inspection--not two (one work hour per fitting, two fittings per airplane) as proposed. However, that figure includes costs for actions associated with access and close up. The cost information below describes only the direct costs of those specific actions required by this AD. We recognize that, in doing the actions required by an AD, operators may incur incidental costs in addition to the direct costs. As explained in the proposed rule, the cost analysis in AD rulemaking actions typicallydoes not include incidental costs such as the time required to gain access and close up, time necessary for planning, or time necessitated by other administrative actions. Those incidental costs, which may vary significantly among operators, are almost impossible to calculate. We have not changed the work-hour estimates in this final rule. \n\nConclusion \n\n\tAfter careful review of the available data, including the comments noted above, we have determined that air safety and the public interest require the adoption of the rule with the change previously described. We have determined that this change will neither increase the economic burden on any operator nor increase the scope of the AD. \n\nCost Impact \n\n\tThere are approximately 708 airplanes of the affected design in the worldwide fleet. We estimate that 411 airplanes of U.S. registry will be affected by this AD, that it will take approximately 2 work hours per airplane to accomplish the required inspection, and that the averagelabor rate is $65 per work hour. The cost of certain parts required to be replaced during this inspection will be between $212 and $585 per airplane. Based on these figures, the cost impact of the required inspection on U.S. operators is estimated to be between $140,562 and $293,865, or between $342 and $715 per airplane, per inspection cycle. \n\n\tWe estimate that it will take approximately 2 work hours per fitting to accomplish the required replacement, and that the average labor rate is $65 per work hour. The cost of each required replacement fitting will be $1,894 per Group 1 airplane and $4,439 per Group 2 airplane. The cost of certain other parts required to be replaced during this replacement will be $292 per Group 1 airplane and $106 per Group 2 airplane. Based on these figures, the cost impact of the required replacement per fitting on U.S. operators is estimated to be between $951,876 and $1,921,425, or $2,316 per Group 1 airplane and $4,675 per Group 2 airplane. \n\n\tThe cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions. \n\nRegulatory Impact \n\n\tThe regulations adopted herein will not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132. \n\n\tFor the reasons discussed above,I certify that this action (1) is not a "significant regulatory action" under Executive Order 12866; (2) is not a "significant rule" under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the location provided under the caption ADDRESSES. \n\nList of Subjects in 14 CFR Part 39 \n\n\tAir transportation, Aircraft, Aviation safety, Incorporation by reference, Safety. \n\nAdoption of the Amendment \n\nAccordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows: \n\nPART 39--AIRWORTHINESS DIRECTIVES \n\n1. The authority citation for part 39 continues to read as follows: \n\n\tAuthority: 49 U.S.C. 106(g), 40113, 44701. \n\n§ 39.13 (Amended) \n\n2. Section 39.13 is amended by adding the following new airworthiness directive: